The present invention relates generally to electric motors incorporating an internal baffle to protect components housed within the motor from exposure to rain, sleet, snow or other contaminants which may enter the motor through ventilation openings.
Many electrical motors for outdoor applications require internal baffles to inhibit water or other contaminants, which may enter openings or vents that allow cooling air to travel through the motor, from contacting the rotor, electrical windings or other electrical components housed within the motors. It is generally known to provide a funnel shaped baffle within a motor housing near air outlet vents in the housing. If water or some other contaminant enters through the outlet vents, the baffle prevents the water or other contaminants from reaching the electrical components, particularly the rotor and electrical windings.
As generally understood, thermal protection of an electric motor is nearly as important as the amount of power produced by the motor. In other words, if a motor is not sufficiently cooled during operation, the motor could overheat, thereby possibly damaging the motor. Illustrated in FIG. 3 is a known electric motor 10 including a housing 12 having therein an inlet vent 14 and an outlet vent 26. A funnel shaped baffle 34, which is press-fit into the housing, is positioned near the outlet vent 26 to inhibit water or other contaminants which may enter through the outlet vent 26 from reaching the internal electrical components, such as the stator winding 18 and rotor 22, of the motor 10. The motor draws cooling air in (representatively shown as arrow A) through the inlet vent 14 and guides the air (representatively shown as arrows B and C) through the motor 10 to cool internal components. The air passes through the baffle 34 (as shown by arrow D), prior to exiting the outlet vent 26. The motor also includes an end frame 38 and a rotor shaft bearing 46.
As can be appreciated, it is desirable for the temperature of the intake air to be less than the temperature of the exhaust air. A problem with the known funnel baffle 34 design shown in FIG. 3 is that it sometimes causes hot exhaust air to be recirculated back into the air inlet vent 14, thereby reducing the cooling efficiency of the motor. As shown in FIG. 3, as the heated air passes through the baffle 34, the air undergoes a change of flow direction, typically an abrupt 180xc2x0 turn (see arrow D in FIG. 3), prior to exiting the outlet vent 26. The sudden change in the direction of air flow results in a pressure loss which reduces the total amount of air flow. Another disadvantage of the sudden change in the direction of air flow is that the abrupt 180xc2x0 turn directs the hot air exiting the outlet vent 26 back into the inlet vent 14 (see arrow E in FIG. 3).
Another problem with the known funnel baffle 34 design is that it does not always adequately shield the rotor shaft bearing 46 (FIG. 3) from exposure to water and other contaminants. This can reduce the operating life of the bearing 46.
Another problem with the known baffle design concerns its manner of assembly. A press machine is needed to mount the baffle 34 within the motor housing 12. This adds undesirable labor costs to the overall assembly of the motor.
Accordingly, there is a need for a new electric motor baffle design which addresses the above noted problems and other problems. A feature of the present invention is to provide an electric motor having a baffle which is supported relative to and within the motor housing, so that the baffle not only substantially prevents water and other contaminants which may enter an outlet vent in the motor housing from contacting certain internal components of the motor, it also allows air passing through the motor housing to exit the outlet vent without first having to radically change flow directions just prior to exiting the outlet vent. The streamlined air flow minimizes pressure loss in the hot exhaust air, so as to reduce the likelihood of the hot exhaust air from being recirculated back into an inlet vent in the motor housing. This greatly increases the cooling efficiency of the motor to better ensure that the motor will not overheat during operation, especially if the motor is operating under full load conditions or producing its maximum power. Another benefit of increasing the cooling efficiency of the motor may result in modifying material specifications for the motor, which may translate into reduced material costs, thereby increasing profitability of the overall motor design.
Another feature of the present invention is to provide an electric motor having a baffle which is supported relative to and within a housing for the motor, such that the baffle is spaced a distance away from an inner surface of the housing to allow air entering an inlet vent in the motor housing to travel around the baffle, as opposed to through the baffle, and out an outlet vent without having to substantially change its direction of flow prior to exiting the outlet vent.
Another feature of the present invention is to provide an electric motor having a baffle which is supported relative to and within a housing for the motor so as to protect a rotor shaft bearing from exposure to water and other contaminants which may enter the motor housing through an air outlet vent. According to one aspect of the invention, the motor includes an end frame which is mounted to the housing and which supports the bearing. The baffle abuts the end frame, and is preferably mounted directly to the end frame, to effectively shield the bearing from exposure to water and other contaminants.
Another feature of the present invention is to provide an electric motor having a baffle which is supported relative to and within the housing without having to use a press machine, thereby reducing labor costs associated with assembling the motor.
In a preferred embodiment, the baffle according to the present invention includes a first ring shaped portion, a second portion forming a part of a frustum extending from the first portion, and a third portion forming a part of a cylinder extending from the second portion. Preferably, when the baffle is mounted to an end frame within a motor housing, the third portion axially overlaps a stator winding and rotor within the housing to substantially prevent water and other contaminants which may enter an outlet vent in the housing from contacting the stator winding and rotor.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features.